docs: def register(cls, klass, name=DEFAULT_DBNAME):
          """Register an Eop Database
  
          The only requirement of this database is that it should have ``__getitem__``
          method accepting MJD as float.
          """
  
          if name in cls._dbs:
              msg = "'{}' is already registered for an Eop database. Skipping".format(name)
              log.warning(msg)
          else:
              cls._dbs[name] = klass